In a steel industry, a hot rolling mill is controlled by strategically located four switches. In addition, there are three sensors located on the mill to provide information on the temperature, speed, and thickness of the products. Write the truth table for switches as AND gates as if they are all connected in series. Write the truth table for sensors as AND gate as if they are all connected in series. List the IO devices
and assign addresses to input and outputs and write a ladder logic program for the operation.

Three switches S1, S2, and S3 are used to control the process and the fourth switch S4 is spared for emergency shut down only. If any two switches S1, S2 and S3 are ON the rollers start operating. If the three switches are ON the steel sheets start rolling. Identify the operating conditions on the truth table. If any of the two sensors indicate an over-load condition the mill slows down. On the truth table identify the operating conditions.